Extracellular matrix in regenerating rat sciatic nerve: a comparative study on the localization of laminin, hyaluronic acid, and chondroitin sulfate proteoglycans, including versican.

Using a glial hyaluronate-binding protein as a probe, monoclonal antibodies against versican and ABC digested chondroitin sulfate proteoglycans, and polyclonal antibodies against laminin, we localized these extracellular matrix (ECM) components in the endoneurium of the adult rat sciatic nerve. During Wallerian degeneration caused by nerve crushing, the staining pattern of these ECM elements changed dramatically. In the first stages and up to 5 days after injury, the tubular endoneurial structures remained the same as in control nerves. Ten days after crush, the bands of Büngner formed by proliferating Schwann cells in the distal stump of crushed nerves stained diffusely for hyaluronate, laminin, and chondroitin sulfate. Regenerating axons were demonstrated in this location by double-labeling experiments with neurofilament antibodies. Conversely, staining with antibodies against versican, a hyaluronate binding proteoglycan, was reduced and the bands of Büngner were not stained. After 30 days the endoneurial tubes made their reappearance and, as in normal nerve, they stained for hyaluronate, laminin, versican, and chondroitin sulfate. It is concluded that proliferating Schwann cells in peripheral nerve undergoing Wallerian degeneration are capable of producing several endoneurial ECM constituents, versican being a notable exception.